(1) Field
The present application relates generally to heart rhythm disorders. More specifically, the present application is directed to a system and method for reconstructing cardiac activation information (activation onset) associated with heart rhythm disorders.
(2) Brief Discussion of Related Art
Heart (cardiac) rhythm disorders are common and represent significant causes of morbidity and death throughout the world. Malfunction of the electrical system in the heart represents a proximate cause of heart rhythm disorders. Heart rhythm disorders exist in many forms, of which the most complex and difficult to treat are atrial fibrillation (AF), ventricular tachycardia (VT) and ventricular fibrillation (VF). Other rhythm disorders are more simple to treat, but may also be clinically significant including atrial tachycardia (AT), supraventricular tachycardia (SVT), atrial flutter (AFL), supraventricular ectopic complexes/beats (SVE) and premature ventricular complexes/beats (PVC). While under normal conditions the sinus node keeps the heart in sinus rhythm, under certain conditions rapid activation of the normal sinus node can cause inappropriate sinus tachycardia or sinus node reentry, both of which also represent heart rhythm disorders.
Treatment of heart rhythm disorders—particularly complex rhythm disorders of AF, VF and polymorphic VT—can be very difficult. Pharmacologic therapy for complex rhythm disorder is not optimal, with poor efficacy and significant side effects. Ablation has been used increasingly in connection with heart rhythm disorders by maneuvering a sensor/probe to the heart through the blood vessels, or directly at surgery, and delivering energy to a location of the heart that harbors a cause of the heart rhythm disorder to mitigate and in some cases to eliminate the heart rhythm disorder. However, in complex rhythm disorders ablation is often difficult and ineffectual because tools that identify and locate a cause of the heart rhythm disorder are poor and hinder attempts to deliver energy to the correct region of the heart to eliminate the disorder.
Certain systems and methods are known for treating simple heart rhythm disorders. In a simple heart rhythm disorder (e.g., atrial tachycardia), consistent activation onset patterns from beat to beat can generally be traced back to an earliest location, which can be ablated to mitigate and in some cases to eliminate the disorder. Even in simple heart rhythm disorders, such ablation of the cause of a heart rhythm disorder is challenging and experienced practitioners often require hours to ablate simple rhythm disorders with consistent beat-to-beat activation patterns, such as atrial tachycardia.
There are no known systems and methods that have been successful with respect to identifying causes for the complex rhythm disorders such as AF, VF or polymorphic VT. In a complex rhythm disorder, an earliest location of activation onsets cannot be identified because activation onset patterns change from beat to beat, and are “continuous” such that there is no identifiable earliest point (or start) or latest point (or end).
Diagnosing and treating heart rhythm disorders often involves the introduction of a catheter having a plurality of sensors/probes into the heart through the blood vessels of a patient. The sensors detect electric activity of the heart at sensor locations in the heart. The electric activity is generally processed into electrogram signals that represent the activation of the heart at the sensor locations.
In a simple heart rhythm disorder, the signal at each sensor location is generally consistent from beat to beat in timing and often in shape and number of its deflections, enabling identification of activation onsets at each sensor location. However, in a complex rhythm disorder, the signal at each sensor location from beat to beat may transition between one, several, and multiple deflections of various shapes. For instance, when a signal for a sensor location in AF includes 5, 7, 11 or more deflections, it is difficult if not impossible to identify which deflections in the signal are at or near the sensor location in the heart (i.e., local activation) versus a further removed location still sensed by the sensor in the heart (i.e., far-field activation) or simply noise from another part of the patient's heart, other anatomic structures, movement or motion of the sensor relative to the heart or external electronic systems.
There are no known systems and methods that have been able to reconstruct cardiac activation information (onsets) in variously shaped signals associated with heart rhythm disorders, especially in complex rhythm disorders, to facilitate identification of a cause of the heart rhythm disorders and their elimination.